The present invention relates to a wastewater treatment agent for flocculating the pollutants contained in polluted water. The present invention relates also to a polluted water purifier and a polluted water purifying method for flocculating and thereby removing the pollutants contained in polluted water. The present invention relates also to a washing machine with a purifier which permits washing using washing wastewater after removing the pollutants contained therein.
Conventionally, polluted water such as wastewater from a washing machine is drained without any treatment. Synthetic detergent contains, as its main ingredient, an anion surfactant (surface-active agent) such as linear sodium alkylbenzenesulfonate (LAS) or an alkylsulfuric ester, which is relatively poorly biodegradable and thus contributes more to water pollution in rivers than soap.
Today, the washing wastewater drained from households is considered to contribute most to water pollution. For this reason, from the viewpoint of protecting the environment, it is desirable to reduce the concentration of pollutants such as a surfactant contained in washing wastewater and purify it before draining it.
To cope with this, for example, Japanese Patent Application Laid-Open No. H9-182896 discloses a washing machine in which a divalent metal chloride is added to washing wastewater so that a surfactant precipitates as a result of salting-out and then the washing wastewater is filtered to remove the precipitate. In this washing machine, as the washing wastewater used in washing is circulated, a flocculant such as calcium chloride is added thereto. The flocculant causes the dirt and detergent contained in the washing wastewater to flocculate and form flocks, and, as the washing wastewater is circulated, it is filtered to remove the flocks and is thereby purified. The washing wastewater thus purified is then used as rinsing water in a rinsing process.
On the other hand, Japanese Patent Application Laid-Open No. H10-118390 discloses a washing machine in which the pollutants such as a surfactant contained in washing wastewater is removed by being made to flocculate and precipitate by electrolysis In this washing machine, a treatment bath having a positive and a negative electrode is provided in the middle of the drainage path of washing wastewater. The washing wastewater is electrolyzed in the treatment bath, and metal cations are produced therein, which cause the dirt and detergent to flocculate and precipitate as flocks. The flocks are then removed, so that purified washing wastewater is drained from the treatment bath.
However, according to the method disclosed in Japanese Patent Application Laid-Open No. H9-182896 mentioned above, since the washing wastewater is purified as it is circulated, the flocculant dissolved in it flows into the washing tub. This causes the dirt and detergent to flocculate and form flocks inside the washing tub. These flocks adhere back to the laundry and are difficult to remove.
Where washing wastewater is cold, aluminum chloride (AlCl3) is widely used as a flocculant. Since AlCl3 is an inorganic flocculant with a relatively low molecular weight, whereas it effectively makes small molecules of a surfactant precipitate as flocks, the flocks thus produced tend to be extremely fine particles.
To filter out and remove such fine particles, it is necessary to use a filter with fine pores, which is prone to be clogged. Thus, to prevent a significant drop in the volume of water treated resulting from an increased loss in pressure, the filter needs to be maintained frequently as by replacement or reverse-flow cleaning.
This problem can be overcome by using a polymer flocculant with high basicity such as polyaluminum chloride (PAC). A polymer flocculant tends to make a surfactant in a solution precipitate as larger flocks, and thus excels AlCl3 in flocculating/removing a surfactant.
However, chelates of PAC with high basicity have high molecular weights, and are thus ineffective against surfactant components having small molecules and dissolved in water. Thus, PAC needs to be added in large amounts, which tends to cause secondary pollution. Therefore, it is vital to reduce the amount of flocculant used without lowering washing performance.
Moreover, PAC exhibits poor solubility in water and poor preservation stability under cold conditions. It is therefore unsuitable for the treatment of washing wastewater in winter. Thus, a wastewater treatment agent is sought that permits pollutants composed of organic substances to flocculate for easy collection under cold conditions.
On the other hand, according to the method disclosed in Japanese Patent Application Laid-Open No. H10-118390 mentioned above, pollutants (a surfactant) are made to precipitate by electrolysis, and the resulting flocks are separated and removed. Therefore, when washing wastewater contains a surfactant in a high concentration, it takes a relatively long time to produce a precipitate, and the operation of the washing machine is thereby hindered.
Thus, to increase the volume of washing wastewater that can be treated so as to ensure smooth operation of the washing machine, it is necessary to secure an extra space where to store washing wastewater temporarily inside the body of the washing machine. This makes the washing machine larger, and makes it difficult to secure the space in which to install it. Moreover, it is difficult to exercise control so as to make pollutants and metal cations react in equivalent amounts, and thus it is impossible to flocculate dirt and detergent to a sufficient degree.
An object of the present invention is to provide an easy-to-maintain polluted water purifier that permits easy separation and removal of dirt and detergent flocks, and to provide a washing machine provided with such a polluted water purifier. Another object of the present invention is to provide a polluted water purifier and a polluted water purifying method that achieve a satisfactory purifying effect with a reduced amount of flocculant. Another object of the present invention is to provide a wastewater treatment agent that permits efficient removal of pollutants composed of organic substances from cold wastewater.
To achieve the above objects, according to the present invention, a wastewater treatment agent flocculates a surfactant component present in wastewater with a primary flocculant composed of a high-molecular-weight inorganic flocculant or a mixture of a high-molecular-weight inorganic flocculant and a low-molecular-weight inorganic flocculant and makes the resulting flocks grow larger with a secondary flocculant composed of a high-molecular-weight organic flocculant.
According to the present invention, a polluted water purifier for collecting a pollutant present in polluted water by flocculating the pollutant with a flocculant, or a washing machine incorporating such a purifier, is provided with: a mixer for mixing the polluted water with the flocculant and air; an agitator for agitating the polluted water, containing the flocculant and the air, that flows into a cylindrical agitation chamber along the inner surface thereof by making the polluted water into a spiraling stream so that the flocks formed by the flocculant hold bubbles; and a separator, connected to the agitator, for temporarily storing the polluted water and for separating the flocks holding the bubbles.
According to the present invention, a polluted water purifier for collecting a pollutant present in polluted water by flocculating the pollutant with a flocculant, or a washing machine incorporating such a purifier, is provided with: a polluted water thank for storing the polluted water, a first mixer for mxiing the polluted water a primary flocculant to produce primary flocks; a second mixer for mixing the polluted water containing the primary flocks with a secondary flocculant and air to produce secondary flocks; an agitator for agitating the polluted water containing the flocculant and the air so as to make the secondary flocks grow larger; and a separator for separating the secondary flocks thus grown. Here, the polluted water tank, the first mixer, the second mixer, the agitator, separator are coupled in this order to form a circulation path that leads back to the polluted water tank.
According to the present invention, a polluted water purifier for collecting a pollutant present in polluted water by flocculating the pollutant with a flocculant, or a washing machine incorporating such a purifier, is provided with: an aspirator for sucking in the flocculant and air to mix the flocculant and the air with the polluted water and thereby produce flocks holding bubbles; and a separator for separating the flocks holding the bubbles from the polluted water.
According to the present invention, a polluted water purifier for collecting a pollutant present in polluted water by flocculating the pollutant with a flocculant, or a washing machine incorporating such a purifier, is provided with: a pH value controller for lowering the pH value of the polluted water by adding an acid to the polluted water.
According to the present invention, a washing machine incorporating a purifier is provided with a water tub having the shape of a bottomed cylinder and a polluted water purifier that collects a pollutant present in washing wastewater by flocculating the pollutant to produce flocks and then separating the flocks by filtering the flocks out with a separator. Here, the separator is fitted detachably to the water tub.
According to the present invention, a washing machine incorporating a purifier is provided with a water tub having the shape of a bottomed cylinder and a polluted water purifier that collects a pollutant present in washing wastewater by flocculating the pollutant to produce flocks and then separating the flocks by filtering the flocks out with a separator. Here, the separator is fitted detachably so as to cover the water tub from above an opening thereof
According to the present invention, a washing machine incorporating a purifier is provided with a polluted water purifier for purifying polluted water drained from a washing tub by removing a pollutant present in the polluted water. Here, halfway through a washing process, washing water is circulated from the washing tub through the polluted water purifier back to the washing tub.
According to the present invention, a washing machine incorporating a purifier and provided with a washing process for removing dirt on laundry with washing water containing a detergent and a first rinsing process for removing the detergent from the laundry is provided with: a reservoir section for storing the drained washing water; and a polluted water purifier for purifying the washing water by collecting a pollutant present in the washing water stored in the reservoir section by flocculating the pollutant. Here, the washing water used in the washing process and rinsing water used in the first rinsing process is stored together in the reservoir section and is purified simultaneously by the polluted water purifier.
According to the present invention, a washing machine incorporating a purifier and provided with a washing process for removing dirt on laundry with washing water containing a detergent and a first rinsing process for removing the detergent from the laundry, is provided with: a reservoir section for storing the drained washing water; and a polluted water purifier for purifying the washing water by collecting a pollutant present in the washing water stored in the reservoir section by flocculating the pollutant. Here, the washing water used in the washing process is purified by the polluted water purifier and is then used in the first rinsing process, and then rising water used in the first rinsing process is purified by the polluted water purifier.
According to the present invention, a method of purifying polluted water by collecting a pollutant present in the polluted water by flocculating the pollutant with a flocculant includes a step of lowering the pH value of the polluted water by adding an acid to the polluted water.